Vacuum system for die casting



Feb. 25, 1964 G. R. MORTON 3,121,926

VACUUM SYSTEM FOR DIE CASTING Filed Nov. 4, 1957 GLEN R. MORTONINVENTOR.

FIG.2. 4.1% I

United States Patent ()fifice 3,121,926 Patented Feb. 25, 1964 3,121,926VACUUM SYSTEM FOR DIE CASTING Glen R. Morton, 7025 S. Sarpy, Omaha,Nebr. Filed Nov. 4, 1957, Ser. No. 694,315 Claims. (Cl. 22-68) Thisinvention relates to die-casting machines and more particularly it is anobject of this invention to provide a more efficient die-casting systemfor vacuum die-casting.

I am aware that others have invented vacuum die-casting systems in whichvalves have been used to close off vacuum outlet grooves in the dies.However, I have discovered by experiment that none of these provide asufficiently well timed and rapid closing of the vacuum groove valve tomake them operable and reliable from the standpoint of preventing largequantities of molten metal from passing into the vacuum system whenusing a large opening out of the cavity.

It is an object of my invention to provide a vacuum system for diecasting machines that makes it possible to have an opening leading fromthe cavity of the die to the vacuum source which opening has a capacitygreater than the rate of displacement of the metal coming into thecavity at the high speed necessary to prevent chilling of the metal atany part before the cavity is completely filled, thus permitting ahigher vacuum and sustained during the casting cycle.

A particular object is to provide a cavity in connection with the vacuumgroove to utilize the directional flow of the metal in case of too muchmetal accidently being ladled or injected into the shot chamber, themetal will flow on into this cavity instead of into the vacuum supplyline, etc. This was a major source of trouble in some of the systemsthat the industry has tried to use.

Another object is to use an accumulated source of hydraulic pressureelectrically controlled for the instantaneous closing of the vacuumgroove valve in the die.

Another object is to provide a vacuum system which uses an accumulatedvacuum for making available vacuum in quantity that is not dissipated ina wasteful manner.

A further object is to provide a vacuum system for a cold shot chambermachine which makes possible a higher vacuum than heretofore forexhausting hydrogen gas caused by moisture in the metal, thereby makingpossible pressure tight castings even when the humidity is as high as100%.

Another object is to provide a metered flow or" metal into the shotchamber under vacuum through small metered holes for regulating flow,for slowing down metal flow to an extent making possible regulation oftiming and further including a means for time delay between applicationof the vacuum to the cavity and forward motion of the plunger to permitmetal in sufficient but not excessive quantities to be driven into theshot chamber by atmospheric pressure as a result of the vacuum drawn onthe cavity and shot chamber.

A further object is to eliminate aluminum oxide in the castings which iscaused by breaking the surface film of the molten metal by ladling, etc.This aluminum oxide in the castings make them very diflicult to machineas the oxide dulls the tools.

By feeding the metal into the shot chamber from beneath the surface inthe bath whereby the metal is not in contact with air until casting iscomplete. A particular object is to provide a system of timing of theclosing of a valve in the bleeder groove sufliciently soon after thecavity has been filled to sufiiciently prevent passage of metal pastthis valve to avoid the problem of the need for shutting down of amachine for the cleaning of the vacuum line which leads from the bleedergroove.

In the drawings:

FIGURE 1 is a diagrammatic view of a portion of a die casting machinewith this invention attached, many parts being shown in section;

FIGURE 2 is a view of the face of the movable die plate of thisinvention.

In FIGURE 1 a molten metal bath and furnace 10 delivers metal through anextension 12 having a housing 14 to a ceramic intake tube 16 having aclosed lower end 18 provided with intake openings 20 one or" which isshown in FIGURE 1. The openings 20 are of small size for metering flowto a speed sufficiently slow that other later described parts of themachine can be timed proportionately thereto.

The extension 16 has its lower end beneath the surface 22 of moltenmetal in the bath 10.

The extension 16 is suitably attached to the underside of the shotchamber 34) and is in communication therewith through an opening 32forwardly of a rearwardmost position of a plunger 34 urged by plungerrod 36 as operated by a piston 38 in a cylinder 40 supported by pedestal42, the cylinder 441 being conventional and operated by hydraulic lines44 at each end thereof.

Metal from the interior 50 of the shot chamber 30 can pass through agroove 82 in the die then through a more constricted groove 84 in themovable die 85 thence through into the cavity 86 through a constrictedgroove 88 into a vacuum groove 90 past a vacuum valve 92 adapted toclose the groove 9% and prevent molten metal from passing through thegroove 90 into a connected vacuum outlet passage 94, which latter is atthe top of the movable die block 85. It will be seen that the vacuumgroove 90 can also be called an outlet groove inasmuch as it serves asan outlet for air in the die cavity.

The movable die block 85 further has a molten metal trap 96 in the formof an indentation into the die section 85 disposed on the other side ofthe passage 94 from the vacuum groove 90 or otherwise in a positionbeneath the passage 94 whereby molten metal tends to collect in the trap96 rather than passing out through the passage 94. The entrance of thetrap is in alignment with the direction of metal flow in the groove andthe groove extends beyond the entrance to the trap in a directiontransverse to the direction of the extending of that portion of thegroove which is before the entrance to the trap with respect to thedirection of metal flow.

A vacuum line 98 is connected to the passage 94 by having its lower endsecured by a bolt 99 to the stationary die section 87 but not secured tothe movable die section 85.

The stationary die section 87 has cavities and the like complemental tothose of the movable die section as is usual.

The vacuum line 98 extends to a valve 102 controlling flow from a vacuumsupply line 104 leading to a source of accumulated vacuum for instantsubstantially undissipatable vacuum supply.

The valve 102 is controlled by a solenoid 208 which has one of itsterminals connected by a wire to a terminal 112 of a solenoid 116.

The solenoid 116 is part of the standard equipment of a die castingmachine and is the solenoid which actuates the timer of the machine whenthe die locks close, the said timer being conventional and not shown.

The solenoid 116 receives energy to its terminal 112 through a line 120extending to circuits of a machine not shown and the other terminal 124of the solenoid receives power from a line 128 extending from circuitsof the machine, not shown.

A Wire extends from the terminal 124 to a terminal 144 of a switch 146.The switch 146 has a rocker arm 148 disposed in a position to beactuated by a finger 150 fixed to the plunger rod 36 at times when theplunger rod has reached a forward position in which the plunger 34 haspassed across the opening 32 and has traveled substantially to itsfarthest forward point.

When the finger in forward travel strikes the rocker arm 143 contact ismade between terminals and 144 of the switch 146, by means of a contactmember 166 of the switch.

This connects the Wire 1140 in circuit with a wire 170 which latterleads to a solenoid 174 of this invention which controls the valve 178which latter permits flow of hydraulic fluid through a line 180 into acylinder 182 for driving a piston 184 to the right for causing the valve92, which is a rod attached to the piston 184, to close.

The hydraulic fluid entering the valve 178 comes through a line from asource of accumulated hydraulic pressure for making possibleinstantaneous action.

The other terminal of the solenoid 174 is connected by a wire 196 to theterminal 112 of the solenoid 116.

Oil returns from the valve 198 through a line 200 to a reservoir notshown. Oil returns from the cylinder 182 during a motion of the piston184 to the right through a hydraulic line 206, which latter connects tothe right hand end of the cylinder 182 while the line 100 connects toits left end.

The solenoid 208 which operates the vacuum valve 102 receives energyfrom the same terminals 112 and 124 and so the valve 162 is onlyenergized when the die is closed and as now described.

A line 212 connects one terminal of the solenoid 208 with the wire 196leading to the terminal 112 and a wire 218 leads from the other terminalof the solenoid 208 to a terminal 220 on the switch 146 which latter isplaced in electrical communication with a terminal 144 of the switch 146by the contact member 166 at times when the rocker arm is in the fullline position shown in FIG- URE 1.

The circuit operates as follows:

The solenoid 208 that actuates the vacuum valve 102 and the solenoid 174that actuates the valve 178 that allows oil to How to the cylinder 182to move the valve 92 to close the vacuum groove 90 are supplied by thesame source, namely the wires 120 and 128 that energize the timer, notshown, that starts the cycle after the die has been closed.

When the die is locked closed a switch, not shown, is closed by thelocking of the toggles of the machines, also not shown. And also notshown is a hand operated switch which is closed by the operator whenhand ladling, thus energizing the vacuum solenoid 208 through the switch146, and also starts the timer, not shown, which times out and startsthe injection plunger 34 by means of the hydraulic cylinder 40 afterdelaying a sufficient time to allow the correct amount of aluminum zincor other alloy to enter the shot chamber 30 under atmospheric pressuredue to vacuum in the cavity and shot chamber.

The double switch 146 is actuated by the finger 150 on the injectionplunger rod 36 as it moves forward, forcing the metal into the cavities.

The switch 146 is adjustable so it cuts the current from the vacuumvalve solenoid 20S and makes the circuit to the solenoid 174 thatactuates the valve 178 allowing hydraulic fluid to close the valve 92shutting off the vacuum groove 90 and preventing molten metal fromflowing into the vacuum system through the vacuum line 98.

The switch 146 is set so that the vacuum valve 102 is shut off and thevalve 92 and the vacuum groove is also shut off sufiiciently soon afterthe cavity is completely filled to sufliciently prevent passage of metalpast the valve 92 to avoid the problem of necessity for shutting downthe machine for the cleaning of the vacuum line.

As soon as the die starts to open this supply of current is cut by asnap-switch, not shown, and as the die unlocks; at the same instant thedie opening solenoid 270 is energized. This same current energizes thesolenoid 272 that actuates the valve 178 for moving the valve 178 into aposition of opposite effect to that of the solenoid 174 whereby oilunder pressure fiows through the line 206 to retract the piston 184 andvalve 92 opening the vacuum groove 90 completely.

The casting is then ejected in the conventional manner. This inventionmakes use of the solenoid 270 which is a conventional part of themachine and which actuates the opening of the die for properly timingthe solenoid 272.

In using my system the operator only has to retract the ejectors of themachine, which are conventional parts not shown, in the usual manner andthereafter the die closes and the cycle is repeated.

It will be seen that the metal can be forced into the cavity at highspeed without decreasing the vacuum as the vacuum is pulled at a greaterspeed than the metal is injected.

As thus described it will be seen that this invention provides theobjectives of greater efficiency, prevention of metal passage into thevacuum lines, and better castings as above set forth.

As thus described it will be seen that this invention provides a vacuumdie casting system which is well timed, operates without clogging,eliminates aluminum oxide, removes the hydrogen gas during highhumidity, because of the high vacuum that can be obtained. Permitsfaster production by the elimination of ladling and the accumulation ofthin flash sticking to the die face in the bleeder groove, which is aproblem with thin bleeds whether using vacuum or not.

From the foregoing description, it is thought to be obvious that avacuum casting machine constructed in accordance with my invention isparticularly well adapted for use, by reason of the convenience andfacility with which it may be assembled and operated, and it will alsobe obvious that my invention is susceptible of some change andmodification without departing from the principles and spirit thereof,and for this reason I do not wish to be understood as limiting myself tothe precise arrangement and formation of the several parts herein shownin carrying out my invention in practice, except as claimed.

I claim:

1. In a die casing machine, the provision of a die section having an airoutlet groove therein leading from the die cavity means comprising avacuum line for drawing a vacuum on said groove, a shot chamber incommunication with said die cavity, a reciprocating shot plunger in saidshot chamber, a vacuum groove shut 01f valve mounted in said die sectionat said vacuum groove for the sudden closing of said groove to preventescape of molten metal into said vacuum line, a hydraulic cylinderassembly mounted on said machine and having a piston, means drivablyconnecting said piston with said groove shut-off valve, a source ofaccumulated hydraulic pressure, means comprising a hydraulic pressurecontrol valve for placing said hydraulic pressure source incommunication with said hydraulic cylinder to close said groove shut-offvalve, an electrically controllable means for controlling said hydraulicpressure control valve, a source of electrical power, a switch means onsaid machine operating in response to forward movement of said plunger,and a circuit connecting said switch means, said electrical powersource, and said electrically controllable means whereby saidelectrically controllable means opens said pressure control valve forthe closing of said groove shut-off valve when said plunger advances andsaid switch is operated thereby, the timing of the closing of saidgroove shut-off valve being sufiiciently soon after the cavity has beenfilled to sufiiciently prevent passage of metal past the groove shut-offvalve to avoid the problem of shutting down the machine for the cleaningof metal from said vacuum line and for providing castings of greatdensity.

2. The combination of claim 1 in which said second controllable means isspecifically a solenoid.

3. The combination of claim 1 in which a vacuum supply line valve isdisposed in said vacuum supply line, controllable means for operatingsaid vacuum line valve, and said switch means and said circuit operatingsaid controllable means for the opening of said vacuum supply line valveafter said die is closed and as said shot plunger moves into said shotchamber.

4. The combination of claim 1 in further combination with: said shotcylinder having an intake opening, an intake tube in communication withsaid intake opening and extending downwardly into said bath sufiicientlyto be beneath the metal in said bath, said intake tube having an openingin its lower end of a small size for metering flow.

5. In a die casting machine the provision of a die section having an airoutlet groove leading from the die cavity, a shot chamber incommunication with said die cavity, a reciprocating shot plunger in saidshot chamber, an air outlet groove shut-off Valve mounted in said diesection at said air outlet groove for the sudden clos ing of said grooveto prevent escape of molten metal from said groove, a hydraulic cylinderassembly mounted on said machine and having a piston, means drivablyconnecting said piston with said groove shut-off valve, a source ofaccumulated hydraulic pressure, means comprising a hydraulic pressurecontrol valve for placing said hydraulic pressure source incommunication with said hydraulic cylinder to close said groove shut-offvalve, an electrically controllable means for controlling said hydraulicpressure control valve, a source of electrical power, switch means onsaid machine operating in response to forward movement of said plunger,and a circuit connecting said switch means, said electrical powersource, and said electrically controllable means whereby saidelectrically controllable means opens said pressure control valve forthe closing of said groove shut-off valve when said plunger advances andsaid switch is operated thereby, the time of the closing of said grooveshut-oil valve being sufficiently soon after the cavity has been filledto sufficiently prevent passage of metal past the groove shut-oll valveto avoid loss of metal through said groove and to permit escape of airfrom the cavity during the filling of the cavity with metal forproviding castings of great density.

6. The combination of claim 5 in which said second controllable means isspecifically a solenoid.

7. The combination of claim 5 which further comprises the presence insaid die cavity of an overflow trap cavity in communication with saidgroove and having an entrance in alignment with the direction of metalflow in said groove, said groove extending beyond the entrance to saidtrap in a direction transverse to the direction of the extending of thatportion of said groove which s before the entrance to said trap, wherebysaid trap is adapted to receive molten metal in the event the flow ofmetal reaches the shut-oif valve before the shut-off valve closes.

8. In a die casting machine, a sectional die having an air outlet grooveleading from its cavity, a vacuum conduit communicating with the airoutlet groove and adapted to be in communication with a vacuum producingmeans, a molten metal supply conduit communicating with the cavity ofsaid die, a vacuum groove shut-oil valve slidably mounted in said dieand located at its air outlet groove for suddenly closing said airoutlet groove to prevent the escape of molten metal into said vacuumconduit, a two-way hydraulic cylinder unit having a piston operativelyconnected to said groove shut-off valve, a source of accumulatedhydraulic pressure, means comprising a hydraulic pressure control valvefor placing said hydraulic pressure source in said hydraulic cylinder ateither side of the piston of said hydraulic cylinder unit, anelectrically operated means for actuating said hydraulic pressurecontrol valve, a movable means on said machine indicating the timeinterval the cavity of the die is substantially filled with moltenmetal, a switch actuated by said last mentioned means, a source ofelectrical power, and a circuit connecting said switch means, saidsource of electrical power, and said electrically operated means,whereby said electrically operated means actuates said pressure controlvalve for closing said shut-off valve when said switch is actuated andclosed by said movable member, the timing of the closing of said grooveshut-off valve being sufficiently soon after the cavity has been filledwith molten metal to sufiiciently prevent passage of metal past thegroove shut-01f valve, thereby preventing the escape of molten metalinto the vacuum conduit and also providing castings of great density.

9. In a die casting machine, a sectional die having an air outlet grooveleading from its cavity, a vacuum conduit communicating with the airoutlet groove and adapted to be in communication with a vacuum producingmeans, a molten metal supply conduit communicating with the cavity ofsaid die, a vacuum groove shut-off valve slidably mounted in said dieand located at its air outlet groove for suddenly closing said airoutlet groove to prevent the escape of molten metal into said vacuumconduit, a two-way hydraulic cylinder unit having a piston operativelyconnected to said groove shut-off valve, a source of accumulatedhydraulic pressure, means comprising a hydraulic pressure control valvefor placing said hydraulic pressure source in said hydraulic cylinder ateither side of the piston of said hydraulic cylinder unit, anelectrically operated means for actuating said hydraulic pressurecontrol valve, a movable means on said machine indicating the timeinterval the cavity of the die is substantially filled with moltenmetal, a switch actuated by said last mentioned means, an electricallyactuate-d valve in said vacuum conduit, a source of electrical power,and a circuit connecting said switch means, said electrically actuatedvalve, said source of electrical power, and said electrically operatedmeans, whereby said electrically operated means actuates said pressurecontrol valve for closing said shut-oil valve when said switch isactuated and closed by said movable member, the timing of the closing ofsaid groove shut-01f valve being sufficiently soon after the cavity hasbeen filled with molten metal to sufficiently prevent passage of metalpast the groove shut-oil? valve, thereby preventing the escape of moltenmetal into the vacuum conduit and also providing castings of greatdensity.

10. Apparatus for casting articles in which a vacuum is used for pullingdie casting material into an article cavity and maintained fully untilthe cavity is at least substantially loaded, said apparatus comprising asplit die having at least two sections and including a die-castingmaterial inlet, an article cavity, and a vacuum passageway communicatingwith said cavity; a shot cylinder communicating with said die-castingmaterial inlet and having an opening therein; a feed tube coupling saidopening with a supply of die-casting materiaLsaid feed tube having anapertured end adapted to be disposed in the supply for metering flow ofdie-casting material through said tube; a piston in said shot cylindermovable from a position where said opening communicates with said diecavity to a position where communication between said opening and thesupply is interrupted and die-casting material in said shot cylinder isforced into said cavity by said piston to load said cavity; conduitmeans secured to one of said sections and slidably engaging the other ofsuch sections for coupling said vacuum passageway, and thereby saidcavity and said shot cylinder with a source of vacuum wherebydie-casting material is drawn into said cavity by References Cited inthe file of this patent UNITED STATES PATENTS During May 29, Daesen Mar.26, Brummer ct al June 3, Halward Jan. 8, Schroeder Sept. 16, Venus Nov.25, Babbitt Feb. 16, Holder Dec. 18, Holder Mar. 19,

1. IN A DIE CASING MACHINE, THE PROVISION OF A DIE SECTION HAVING AN AIROUTLET GROOVE THEREIN LEADING FROM THE DIE CAVITY MEANS COMPRISING AVACUUM LINE FOR DRAWING A VACUUM ON SAID GROOVE, A SHOT CHAMBER INCOMMUNICATION WITH SAID DIE CAVITY, A RECIPROCATING SHOT PLUNGER IN SAIDSHOT CHAMBER, A VACUUM GROOVE SHUT OFF VALVE MOUNTED IN SAID DIE SECTIONAT SAID VACUUM GROOVE FOR THE SUDDEN CLOSING OF SAID GROOVE TO PREVENTESCAPE OF MOLTEN METAL INTO SAID VACUUM LINE, A HYDRAULIC CYLINDERASSEMBLY MOUNTED ON SAID MACHINE AND HAVING A PISTON, MEANS DRIVABLYCONNECTING SAID PISTON WITH SAID GROOVE SHUT-OFF VALVE, A SOURCE OFACCUMULATED HYDRAULIC PRESSURE, MEANS COMPRISING A HYDRAULIC PRESSURECONTROL VALVE FOR PLACING SAID HYDRAULIC PRESSURE SOURCE INCOMMUNICATION WITH SAID HYDRAULIC CYLINDER TO CLOSE SAID GROOVE SHUT-OFFVALVE, AN ELECTRICALLY CONTROLLABLE MEANS FOR CONTROLLING SAID HYDRAULICPRESSURE CONTROL VALVE, A SOURCE OF ELECTRICAL POWER, A SWITCH MEANS ONSAID MACHINE OPERATING IN RESPONSE TO FORWARD MOVEMENT OF SAID PLUNGER,AND A CIRCUIT CONNECTING SAID SWITCH MEANS, SAID ELECTRICAL POWERSOURCE, AND SAID ELECTRICALLY CONTROLLABLE MEANS WHEREBY SAIDELECTRICALLY CONTROLLABLE MEANS OPENS SAID PRESSURE CONTROL VALVE FORTHE CLOSING OF SAID GROOVE SHUT-OFF VALVE WHEN SAID PLUNGER ADVANCES ANDSAID SWITCH IS OPERATED THEREBY, THE TIMING OF THE CLOSING OF SAIDGROOVE SHUT-OFF VALVE BEING SUFFICIENTLY SOON AFTER THE CAVITY HAS BEENFILLED TO SUFFICIENTLY SOON AFTER THE CAVITY HAS BEEN FILLED TOSUFFICIENTLY PREVENT PASSAGE OF METAL PAST THE GROOVE SHUT-OFF VALVE TOAVOID THE PROBLEM OF SHUTTING DOWN THE MACHINE FOR THE CLEANING OF METALFROM SAID VACUUM LINE AND FOR PROVIDING CASTINGS OF GREAT DENSITY.